GAZA CITY, Gaza Strip — A beleaguered Palestinian President Mahmoud Abbas declared a state of emergency and disbanded the Hamas-led unity government after the Islamic militant group vanquished its Fatah rivals and effectively took control of the Gaza Strip yesterday.Fearful that Hamas’ momentum could spread to the West Bank, Fatah went on the offensive there, rounding up three dozen Hamas fighters. Angry militants threw office furniture out a third-story window of the Palestinian parliament building in Ramallah, then set fire to the office of three Hamas lawmakers. A Hamas activist was shot and killed in Nablus, the first person to be killed in the West Bank after days of violence in Gaza; the Al Aqsa Martyrs’ Brigades, a violent Fatah offshoot, claimed responsibility.

In Gaza, it was a day of major victories for Hamas and its backers in Iran and Syria — and of devastating setbacks for the Western-backed Fatah. In one particularly humiliating scene, masked Hamas fighters marched agents of the once-feared Preventive Security Service out of their headquarters, arms raised in the air, stripped to the waist and ducking at the sound of a gunshot.

The violence has killed at least 90 people in the past five days, including 33 on Thursday alone. Witnesses, Fatah officials and a doctor reported executions by Hamas militants of defeated Fatah fighters yesterday; Fatah said seven of its men were shot in the head gangland-style. Hamas denied any such killings.

Abbas, of Fatah, fired the Hamas prime minister and said he would install a new government, replacing the Hamas-Fatah coalition formed just three months ago. Abbas’ decrees, which he issued in Ramallah, won’t reverse the Hamas takeover of Gaza. Instead, his moves will enable Fatah to consolidate its control over the West Bank, likely paving the way for two separate Palestinian governments.

Because Fatah has recognised Israel’s right to exist and signed on to past peace agreements, the international community’s boycott of the Palestinian territories in the wake of Hamas’ electoral successes may no longer apply to the West Bank — just to Gaza. Some 2 million Palestinians live in the West Bank, while 1.4 million reside in Gaza.

Hamas’ success has thrown into turmoil everything from Mideast peacemaking to Palestinian statehood to relations with Israel and the West.

“The era of justice and Islamic rule has arrived,” Hamas spokesman Islam Shahawan said.

Fatah’s old demons — corruption, petty quarreling, lack of leadership — led to its dismal performance. While disciplined Hamas systematically hoarded weapons, Fatah’s Gaza leader, Mohammed Dahlan, preferred travel and West Bank politics to preparing for the inevitable showdown with the Islamic militants. Dahlan returned Thursday from Egypt, where he stayed several weeks after knee surgery. But instead of going to Gaza, he headed for Ramallah.

Many West Bank Palestinians, watching the fall of Gaza on their TV screens, pinned the blame on Abbas, whom they see as indecisive and detached. During Hamas’s assaults in Gaza this week, no prominent Fatah leader was in the coastal strip to take command.

“Hamas has leadership, a goal, an ideology and funding,” said Gaza analyst Talal Okal. “Fatah has neither leadership, nor a goal, a vision or money.”

By capturing Gaza City’s three main security compounds and the southern town of Rafah, Hamas secured its hegemony in Gaza, putting Islamic extremists in control there. The final target for Hamas was Abbas’ Gaza City headquarters, which fell without a fight late yesterday as some officials fled by boat in the direction of Egypt.

For first time since fighting erupted five days ago, Abbas issued an order to strike back. But his words were too little, too late.

Hamas spokesman Sami Abu Zuhri said Abbas’ decisions have “no value” on the ground.

Israeli Defence Minister Amir Peretz vowed not to let the takeover of Gaza spill over into violence against Israel. Some Israelis said only a Gaza invasion could curb Hamas’ military power. But for now, the government seems more inclined to stay out, fearful of inviting more rocket attacks on southern Israel.

In Washington, Secretary of State Condoleezza Rice said the United States backs Abbas’ move. Abbas informed Rice of his decision in a phone call earlier yesterday.

“President Abbas has exercised his lawful authority as president of the Palestinian Authority, as leader of the Palestinian people,” Rice said.

“We fully support him in his decision to try and end this crisis for the Palestinian people and to give them an opportunity ... to return to peace and a better future.”

The European Commission, meanwhile, suspended tens of millions of dollars in humanitarian aid projects in the Gaza Strip because of the escalating violence, a day after the U.N. announced it would scale back its relief projects there.

This week’s fighting has been the most intense since Hamas won parliamentary elections last year, setting the stage for a violent power struggle with Fatah. Hamas reluctantly brought Fatah into the coalition in March to quell an earlier round of violence, but the uneasy partnership began crumbling last month over control of the powerful security forces.

No battle was more indicative of Gaza’s hatreds and passions than the one at Preventive Security, one of Fatah’s four main security bases in the coastal strip. After Hamas fighters overran it in a hail of mortar and gunfire yesterday, they touched their heads to the ground in prayer and marched vanquished gunmen into the streets shirtless.